Former British cabinet minister Chris Huhne has announced he is stepping down from parliament after pleading guilty to perverting the course of justice.

The former energy secretary was due to stand trial alongside ex-wife Vicky Pryce on charges that he made her take speeding points on his behalf.

He changed his plea as the case was about to open at London's Southwark Crown Court this morning.

Making a statement outside the court afterwards, the Liberal Democrat said: "Having taken responsibility for something that happened ten years ago, the only proper course of action for me is to resign my Eastleigh seat in parliament, which I will do shortly."

British Prime Minister David Cameron's official spokesman declined to comment on the resignation, saying only: "It is a matter for Mr Huhne."

Huhne is facing a possible prison sentence as perverting the course of justice often carries a custodial sentence, with a maximum of up to life imprisonment.

His ex-wife previously pleaded not guilty to a charge of perverting the course of justice between 12 March, 2003 and 21 May, 2003 on the grounds of marital coercion.

She is accused of falsely taking speeding points for her ex-husband.

It had been alleged that Huhne, who stood down from the cabinet after he was charged last year, persuaded the 60-year-old economist to take the points so he could avoid prosecution.

The events that led to the charges date back to March 2003 when Huhne's car was allegedly caught by a speed camera on the motorway between Stansted Airport in Essex and London.

The allegations emerged in 2011 after Huhne's 26-year marriage ended when he admitted an affair with PR adviser Carina Trimingham, who was in the public gallery in court today.